// 参数带值 mixin
@mixin border-radius($radius) {
    -webkit-border-radius: $radius;
    border-radius: $radius;
}

.box {
    @include border-radius(3px);
}


// 参数不带值 mixin 
@mixin border-radius($radius:5px) {
    -webkit-border-radius: $radius;
    border-radius: $radius;
}

button {
    @include border-radius;
}



// 参数带多个值 mixin
@mixin center($width, $height) {
    width: $width;
    height: $height;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -($height) / 2;
    margin-left: -($width) / 2;
}

.box-center {
    @include center(500px, 300px);
}


